1. Field of Invention
This invention relates generally to biofeedback systems, and in particular to a system for use by an exerciser whose rhythmic physical activity is translated into an audible musical rhythm which makes it possible for the exerciser to bring his activity into harmony with a musical rhythm that is conducive to optimal conditions of exercise.
2. Status of Prior Art
An individual's ability to mentally control certain of his physiological functions such as body temperature or blood pressure is known as self-regulation. For hundreds of years in the Far East, Yogis and Zen Buddhists have practiced the art of self-regulation. But with the exception of those committed to transcendental meditation, self-regulation techniques have not been widely practiced in Western society, possibly because many disorders induced or aggravated by stress which lend themselves to alleviation by self-regulation can more readily be treated by medication. Thus, a muscle contraction or tension headache as well as migrane, a vascular headache that is more painful than a tension headache, can, to some degree, be relieved by aspirin and other drugs. Such medication does not do away with stress factors responsible for the headache but serves only to moderate the symptoms. Moreover, aspirin and other drugs, when taken frequently and in large doses, often have deleterious side effects.
In recent years, biofeedback techniques have been developed which represent a more effective form of self-regulation. In biofeedback, an involuntary or unconscious physiologic process, such as the heart beat or the brain wave, is made perceptible to the senses, thereby making it possible for the individual to manipulate the process by conscious mental control.
Stress is expressed in many ways, and may be manifested by a headache or by high blood pressure. Of overriding importance in stress therapy is learning to relax and thereby reduce tension and its physiological consequences. With biofeedback, one is able to achieve mental and physical relaxation by being fed back information regarding an unconscious physiological process. This information is derived by means of a non-invasive sensor which measures peripheral skin temperature or skin resistance, heart rate, blood pressure, pulse rate, and some other process variable.
Thus, a signal from an electromyograph is indicative of varying levels of muscular activity; the higher the signal amplitude, the greater the amount of muscular tension. A high level of muscular tension reflects a high degree of stress, giving rise to tension headaches, facial pain and tics, and other stress-related illnesses. By means of a biofeedback system, one can monitor a specific physiologic process and derive therefrom a visible or audible signal indicative of the process. In this way, the user can manipulate the process being monitored by learning to control the signal it yields. By biofeedback one can reduce muscle tension, slow down a rapid heart rate, regulate blood flow to alleviate circulatory problems and, in general, relax the nervous system.
U.S. Pat. No. 4,461,301 to Ochs shows the basic elements of a biofeedback system of the electronic type. In this system, a sensor serves to produce an analog signal representing the physiological function to be regulated, this signal being digitized to provide a digital display indicating changes in this function. In the Shiga U.S. Pat. No. 4,354,505, a signal derived from the brain of the user acts to frequency modulate an audio oscillator to provide in a loudspeaker an audible sound whose pitch is indicative of the brain activity and serves to facilitate training directed toward relaxation from stress.
It is now recognized that one can relieve stress through exercise, for exercise induces relaxation. (See "Relaxation Through Exercise"--Institute for the Advancement of Health, Vol. 3, No. 3--Summer 1986--pp 56-59.)
The concern of the present invention is an an exercise or sports activity that is rhythmic in nature, such as jogging which involves rhythmic leg activity, or boxing a punching bag which involves a rhythmic arm activity.
In order to gain the greatest amount of benefit from such rhythmic physical activity, the two feet or arms should operate in exact phase opposition. Thus, if one were to convert each cycle of activity into a sinusoidal wave having a positive half cycle representing the forward stroke of the right foot or arm and a negative half cycle representing the forward stroke of the left foot or arm, these half cycles would be of equal duration and amplitude. But in practice, this ideal relationship is difficult to attain and requires training.
It is also important that the frequency or repetition rate of this physical activity lie within a range that is beneficial to the exerciser. Thus, a particular jogger, if he jogs above a certain speed, may quickly become exhausted and he may possibly overtax his heart; but if his jogging speed is too slow, he may gain little benefit from the exercise.
The present invention takes into account the ability of most individuals to respond to the rhythm of music and the fact that they are highly sensitive to even small changes in beat. On the other hand, these individuals may find it difficult to coordinate the movement of their arms or feet with an audible rhythm.
This is the problem experienced when learning to dance; for while the novice dancer has no difficulty in humming along with music as it is being played and in mentally following its beat, he has difficulty in bringing his leg movement in harmony with the beat of the music. Thus, a novice dancer may be familiar with the beat of a waltz, a polka or a fox trot, and knows when the music he hears has the correct beat; but it takes training on his part to move his feet in harmony with the rhythm of the music being performed.
Conversely, if a novice dancer were to hear music whose rhythm were synchronized with the movement of his feet, he would be quick to recognize from the resultant beat of the music that his feet were not producing the desired rhythm. The reason the exerciser is able to sense such disharmony is that his brain has stored in its memory the rhythmic patterns characteristic of various species of music and is therefore sensitive to deviations from these patterns. To give a simple example, if an individual were to hear waltz music being played, and the rhythm of the music were controlled by the movement of his feet, the music would sound right to him only if his feet produced a beat appropriate to a waltz.